Method for preparing encapsulated phase change materials

• US 4,505,953 A
• Filed: 06/13/1983
• Issued: 03/19/1985
• Est. Priority Date: 02/16/1983
• Status: Expired due to Term

• Current Assignee: Atochem North America Inc (Arkema)
• Original Assignee: Pennwalt Corporation (Arkema)
• Inventors: Chen, Johnson C. H., Eichelberger, John L.
• Primary Examiner(s): Lusignan, Michael R.
• Application Number:
  US06/504,029
• Time in Patent Office: 645 Days
• Field of Search: 427/213, 427/214, 427/221, 427/3, 427/212, 252/70, 523/200, 523/207, 523/210, 523/211, 428/403, 428/407, 428/304.4, 428/221, 264/7, 165/53, 165/104.17
• US Class Current: 427/212
• CPC Class Codes: C09K 5/063 Materials absorbing or liberating heat during crystallisation; Heat storage materials
• CPC Class Codes: E04C 2/52 with special adaptations for auxiliary purposes, e.g. serving for locating conduits E04C2/54 takes precedence; block-shaped elements therefor E04C1/39; floor structures incorporating ducts E04B5/48
• CPC Class Codes: F24S 60/10 using latent heat
• CPC Class Codes: F28D 20/023 the latent heat storage material being enclosed in granular particles or dispersed in a porous, fibrous or cellular structure
• CPC Class Codes: Y02B 10/20 Solar thermal
• CPC Class Codes: Y02E 10/40 Solar thermal energy, e.g. solar towers
• CPC Class Codes: Y02E 60/14 Thermal energy storage

Abstract

A thermal energy storage composite pellet-shaped product of about 1/8 inch to 1 inch in size, formed of an outer seamless shell member which defines a cavity that permanently encases a phase-change composition, the composition being present in a quantity such that the total volume of the composition, whether in its solid form, liquid form, or both forms as in its transition state, never exceeds the volume of the cavity; and a process for making the product which includes using the phase-change composition in a compacted powder form as cast about which the shell member is formed by roll-coating steps.

Claims

1. A process for manufacturing a thermal energy storage phase-change composite product, comprising:

(a) selecting a thermal energy storage phase-change composition having a phase-change transition temperature within the temperature range of the contemplated environment in which the product is to be used, and maintaining the temperature of the composition below the melting point of the composition, after the composition has been first melted, to provide a solidified thermal energy phase-change composition;

(b) converting the solidified thermal energy storage phase-change composition of (a) to a flowable powder to provide a flowable powder composition while maintaining the composition at a temperature below its melting point;

(c) compacting and pelletizing the flowable powder composition of (b) to form discrete pellet-shaped compacted powder structures having a longest dimension of from about 1/8 inch to about 1 inch and a shortest dimension of at least about 1/8 inch while maintaining a temperature below the melting point of the composition, the degree of compacting being controlled to provide compacted powder structures of sufficient integrity to withstand coating with a wall-forming material as well as an apparent solid density that is less than or equal to the liquid density of the phase-change composition;

(d) coating each of the compacted powder compositions with a curable liquid wall-forming material comprising from about 5% to 30% by weight of the product based upon the final cured weight of the wall-forming material, while maintaining a temperature below the melting point of the composition, said wall-forming material when in a cured state being nonreactive with and substantially impermeable to both the phase-change composition and water; and

then

(e) curing the liquid wall-forming material on each of the compacted powder compositions to form a permanent seamless shell, that is substantially impermeable to and non-reactive with both the phase-change composition and water, which encapsulates each of the compacted powder compositions to provide the product;

said product being capable of dispersion throughout rigid building construction components without causing fracture or damage to the components or product upon repeated thermal change cycles of the encapsulated thermal phase-change storage composition.

2. The process of claim 1 wherein in (d) multiple coats of the liquid wall-forming material are applied.

3. The process as defined in claim 1 wherein in (c) the outer surfaces of the structures are convex shaped with rounded edges.

4. The process as defined in claim 1 wherein in (d) the wall-forming material is selected from the group consisting of a copolymer latex of butadiene-acrylonitrile, a copolymer of vinylidene chloride-acrylic, resinous latexes, rubber latexes, epoxy polymers, polyurethane polymers, acrylic polymers, cellulose acetate and polyamides.

5. The processs as defined in claim 1 wherein in (d) the compacted powder structures are first coated with a water-resistant primer substance.

6. The process as defined in claim 1 wherein in (d) the compacted powder structures are first coated with a water-resistant primer substance selected from the group consisting of asphaltic material or an acrylic polymer or copolymer material.

7. The process as defined in claim 1 wherein in (d) the compacted structures are first coated with a water-resistant primer substance comprising less than about 5% by weight of the structure.

8. The process as defined in claim 2 wherein mica or similar material is coated onto at least one of the coatings of the structure.

9. The process as defined in claim 1 wherein in (a) the phase-change composition has a liquid density that is at least 85% but less than 100% of the solid density of the composition.

10. The process as defined in claim 9 wherein in (a) the composition has a phase-change transition temperature within the range of about 7°

C. to 90°

C.

11. The process as defined in claim 1 wherein in (a) the phase-change composition is selected from the group consisting of glauber salt eutectic mixture, sodium hydroxide, polyethylene, sodium sulfate decahydrate, sodium thiosulphate pentahydrate, calcium chloride hexahydrate, magnesium nitrate hexahydrate, the eutectic of magnesium nitrate hexahydrate and ammonium nitrate, potassium fluoride tetrahydrate, sodium acetate trihydrate, stearic acid, the eutectic of naphthalene and benzoic acid and paraffinic hydrocarbons.

12. The process as defined in claim 1 wherein in (b) a binder material is added to the flowable powder composition to improve integrity in subsequent pelletizing in step (c).

13. The process as defined in claim 1 wherein in (b) fillers are added to the flowable powder composition to provide an apparent solid density after pelletizing in (c) that is less than or equal to the liquid density of the phase-change composition of (a).

14. A process for manufacturing a thermal energy storage phase-change composite product, comprising

(a) selecting a thermal energy storage phase-change composition having a phase-change transition temperature within the temperature range of the contemplated environment in which the product is to be used;

(b) melting the composition to provide a liquid composition;

(c) maintaining the temperature of the liquid composition at a temperature just above the composition melting point and then forming discrete shaped structures of the composition by agglomerating the composition with agglomerator means to provide structures having a longest dimension of from about 1/8 inch to about 1 inch and a shortest dimension of at least about 1/8 inch and then maintaining the temperature of the structures at a temperature below the melting point of the composition, said agglomerating being controlled to provide structures having an apparent solid density that does not exceed the liquid density of the phase-change composition;

(d) coating each of the structures with a curable liquid wall-forming material comprising from about 5% to 30% by weight of the product based upon the final cured weight of the wall-forming material, while maintaining a temperature below the melting point of the composition, said wall-forming material when in a cured state being nonreactive with and impermeable to both the phase-change composition and water; and

then

(e) curing the liquid wall-forming material on each of the structures to form a seamless shell, that is substantially impermeable to and non-reactive with both the phase-change composition and water, which encapsulates each of the compacted powder compositions to provide the product;

said product being capable of dispersion throughout rigid building construction components without causing fracture or damage to the components or product upon repeated thermal change cycles of the encapsulated thermal phase-change storage composition.

15. The process as defined in claim 14 wherein in (d) multiple coats of a liquid wall-forming material are applied.

16. The process as defined in claim 14 wherein in (c) the outer surfaces of the structures are convex shaped with rounded edges.

17. The process as defined in claim 14 wherein in (d) the wall-forming material is selected from the group consisting of a copolymer latex of butadiene-acrylonitrile, a copolymer of vinylidene chloride-acrylic, resinous latexes, rubber latexes, epoxy polymers, polyurethane polymers, acrylic polymers, celluose acetate and polyamides.

18. The process as defined in claim 14 wherein in (d) the structures are first coated with a water-resistant primer substance.

19. The process as defined in claim 14 wherein in (d) the structures are first coated with a water-resistant primer substance selected from the group consisting of asphaltic material or an acrylic polymer or copolymer material.

20. The process as defined in claim 15 wherein mica is coated onto at least one of the coatings of the structure.

21. The process as defined in claim 14 wherein in (a) the phase-change composition has a liquid density that is at least 85% of the solid density of the composition.

22. The process as defined in claim 14 wherein in (a) the phase-change composition is selected from the group consisting of glauber salt eutectic mixture, sodium hydroxide, polyethylene, sodium sulfate decahydrate, sodium thiosulfate pentahydrate, calcium chloride hexahydrate, magnesium nitrate hexahydrate, the eutectic of magnesium nitrate hexahydrate and ammonium nitrate, potassium fluoride tetrahydrate, sodium acetate trihydrate, stearic acid, the eutectic of napthalene and benzoic acid and paraffinic hydrocarbons.

23. The process as defined in claim 14 wherein in (c) the agglomerating means are selected from the group of agglomerating means consisting of rotating pan agglomerator, fluidized bed agglomerator, or a combination of a rotating pan and fluidized bed agglomerator.